Omega Men&#39;s 3557.50.00 Speedmaster Broad Arrow Olympic Edition Automatic Chronograph Watch Quality Swiss Automatic movement; Functions without a battery; Powers automatically with the movement of your arm Domed, anti-reflective scratch-resistant sapphire crystal Case diameter: 42 mm Stainless-steel case; Black dial; Date function; Chronograph functions; Tachymeter function Water resistant to 330 feet (100 M): suitable for snorkeling, as well as swimming, but not diving